public async override Task Invoke(IOwinContext owinContext)
{
System.Web.HttpContextBase context = owinContext.Get <System.Web.HttpContextBase>(typeof(System.Web.HttpContextBase).FullName);
Debug.WriteLine("UrlLocalizationMiddleware::Invoke -- ContentType: {0},\n\tUrl: {1}\n\tRawUrl:{2}", context.Response.ContentType, context.Request.Url, context.Request.RawUrl);
// Establish the language for the request. That is, we need to call
// context.SetPrincipalAppLanguageForRequest with a language, got from the URL,
// the i18n.langtag cookie, the Accept-Language header, or failing all that the
// default application language.
// · If early URL localizer configured, allow it to do it.
var rootServices = LocalizedApplication.Current.RootServices;
if (UrlLocalizer.UrlLocalizationScheme != UrlLocalizationScheme.Void &&
rootServices.EarlyUrlLocalizerForApp != null)
{
rootServices.EarlyUrlLocalizerForApp.ProcessIncoming(context);
}
// · Otherwise skip the URL aspect and detemrine from the other (inferred) attributes.
else
{
context.SetPrincipalAppLanguageForRequest(context.GetInferredLanguage());
}
await Next.Invoke(owinContext);
}
// Implementation
// Events handlers
/// <summary>
/// Handler for the BeginRequest ASP.NET request pipeline event, where we inject our
/// Early URL Localization logic.
/// </summary>
private void OnBeginRequest(object sender, EventArgs e)
{
System.Web.HttpContextBase context = System.Web.HttpContext.Current.GetHttpContextBase();
DebugHelpers.WriteLine("LocalizingModule::OnBeginRequest -- sender: {0}, e:{1}, ContentType: {2},\n\tUrl: {3}\n\tRawUrl:{4}", sender, e, context.Response.ContentType, context.Request.Url, context.Request.RawUrl);
// Establish the language for the request. That is, we need to call
// context.SetPrincipalAppLanguageForRequest with a language, got from the URL,
// the i18n.langtag cookie, the Accept-Language header, or failing all that the
// default application language.
// · If early URL localizer configured, allow it to do it.
if (UrlLocalizer.UrlLocalizationScheme != UrlLocalizationScheme.Void &&
m_rootServices.EarlyUrlLocalizerForApp != null)
{
m_rootServices.EarlyUrlLocalizerForApp.ProcessIncoming(context);
}
// · Otherwise skip the URL aspect and detemrine from the other (inferred) attributes.
else
{
context.SetPrincipalAppLanguageForRequest(context.GetInferredLanguage());
}
}
/// <summary>
/// Implements the Early Url Localization logic.
/// <see href="https://docs.google.com/drawings/d/1cH3_PRAFHDz7N41l8Uz7hOIRGpmgaIlJe0fYSIOSZ_Y/edit?usp=sharing"/>
/// </summary>
public void ProcessIncoming(
System.Web.HttpContextBase context)
{
// Is URL explicitly excluded from localization?
if (!m_urlLocalizer.FilterIncoming(context.Request.Url))
{
return;
} // YES. Continue handling request.
bool allowRedirect =
context.Request.HttpMethod.Equals("GET", StringComparison.OrdinalIgnoreCase) ||
context.Request.HttpMethod.Equals("HEAD", StringComparison.OrdinalIgnoreCase);
// NO. Is request URL localized?
string urlNonlocalized;
string langtag = m_urlLocalizer.ExtractLangTagFromUrl(context, context.Request.RawUrl, UriKind.Relative, true, out urlNonlocalized);
if (langtag == null)
{
// NO.
// langtag = best match between
// 1. Inferred user languages (cookie and Accept-Language header)
// 2. App Languages.
LanguageTag lt = context.GetInferredLanguage();
// If redirection allowed...redirect user agent (browser) to localized URL.
// The principle purpose of this redirection is to ensure the browser is showing the correct URL
// in its address field.
if (allowRedirect)
{
RedirectWithLanguage(context, context.Request.RawUrl, lt.ToString(), m_urlLocalizer);
return;
}
// Otherwise, handle the request under the language infered above but without doing the redirect.
// NB: this will mean that the user agent (browser) won't have the correct URL displayed;
// however, this typically won't be an issue because we are talking about POST, PUT and DELETE methods
// here which are typically not shown to the user.
else
{
context.SetPrincipalAppLanguageForRequest(lt);
return; // Continue handling request.
}
}
// YES. Does langtag EXACTLY match an App Language?
LanguageTag appLangTag = LanguageHelpers.GetMatchingAppLanguage(langtag);
if (appLangTag.IsValid() &&
appLangTag.Equals(langtag))
{
// YES. Establish langtag as the PAL for the request.
context.SetPrincipalAppLanguageForRequest(appLangTag);
// Rewrite URL for this request.
context.RewritePath(urlNonlocalized);
// Continue handling request.
return;
}
// NO. Does langtag LOOSELY match an App Language?
else if (appLangTag.IsValid() &&
!appLangTag.Equals(langtag))
{
// YES. Localize URL with matching App Language.
// Conditionally redirect user agent to localized URL.
if (allowRedirect)
{
RedirectWithLanguage(context, urlNonlocalized, appLangTag.ToString(), m_urlLocalizer);
return;
}
}
// NO. Do nothing to URL; expect a 404 which corresponds to language not supported.
// Continue handling request.
}